The present invention relates to a musical tone signal generating apparatus and, more particularly, to a musical tone signal generating apparatus of a harmonic combination type wherein a fundamental wave and its harmonic wave are generated, and these waves are weighted with the corresponding amplitude coefficients to generate a musical tone signal.
In a conventional musical signal generating apparatus of this type, the amplitude coefficients (to be referred to as harmonic coefficients hereinafter) for controlling the amplitudes of a fundamental wave and harmonic waves (to be referred to harmonic components hereinafter) are properly set to generate musical tone signals having different tone colors.
In a conventional technique as described in, for example, U.S. Pat. No. 3,913,442, the harmonic coefficients of the harmonic components are changed over time to generate a musical tone signal with a tone which changes as a function of time as in an acoustic musical instrument.
In this conventional technique, however, in order to make the amplitudes of harmonic components changeable as a function of time, there is provided an envelope memory (i.e., an attack/decay memory) storing an entire envelope shape of each harmonic component. The number of envelope memories is the same as that of harmonic components. Furthermore, sets of envelope memories must be arranged in units of tone colors. As a result, a large-capacity memory must be used, and the apparatus as a whole becomes large and expensive, resulting in inconvenience.